Polyolefins stabilized with 4,4&#39;-methyl-enebis(2,6-disubstituted phenol)and process thereof

ABSTRACT

POLYOLEFIN STABILIZED WITH A COMPOUND OF THE FOLLOWING FORMULA IS DISCLOSED:   CH2-(3-R1,4-(HO-),5-R2-PHENYL)(3-R3,4-(HO-),5-R4-PHENYL)   WHEREIN R1,R2,R3, AND R4 ARE INDEPENDENTLY ARALKYL OR ALKYL WITH THE PROVISO THAT AT LEAST ONE ARALKYL GROUP CONTAINS NO BRANCHING ON THE CARBON ALPHA TO THE PHENYLENE GROUP OR AT LEAST ONE ALKYL GROUP CONTAINS NO BRANCHING ON THE CARBON ALPHA TO THE PHENYLENE GROUP BUT HAS AT LEAST ONE BRANCH ON THE CARBON BETA TO THE PHENYLENE GROUP.

United States Patent 3,823,115 POLYOLEFINS STABILIZED WITH 4,4'-METHYL-ENEBIS(2,6 DISUBSTITUTED PHENOL) AND PROCESS THEREOF Gordon D. Brindell,Crystal Lake, and. Rudolf F. Macander, Cary, Ill., assignors to TheQuaker Oats Company, Chicago, Ill. No Drawing. Filed May 15, 1972, Ser.No. 253,148 Int. Cl. C0815 45/58 US. Cl. 260-4595 R 16 Claims ABSTRACTOF THE DISCLOSURE Polyolefin stabilized with a compound of the followingformula is disclosed:

l no@-om@-on wherein R R R and R are independently aralkyl or alkyl withthe proviso that at least one aralkyl group contains no branching on thecarbon alpha to the phenylene group or at least one alkyl group containsno branching on the carbon alpha to the phenylene group but has at leastone branch on the carbon beta to the phenylene group.

BACKGROUND OF THE INVENTION Field of the invention This inventionrelates to polyolefin stabilized against oxidative deterioration.

Description of the prior art In US. Pat. No. 3,227,678, the patenteedisclosed a class of phenolic compounds having the following formula asstabilizers for polypropylene:

R R I I wherein R is a lower alkyl group having 1 to 6 carbon atoms,which may be primary, secondary, or tertiary. Typical of those compoundswere 4,4'-methylenebis(2,6- dimethylphenol), 4,4methylenebis(2,6-diisopropylphe- 1101), and4,4'-methylenebis(2,6-di-tert-butylphenol).

SUMMARY OF THE INVENTION The purpose of the present invention is todisclose and claim a class of phenolic compounds which are unexpectedlygood antioxidants for polyolefins.

The present invention may be briefly described as polyolefin stabilizedwith a phenolic compound having the following structural formula:

(Formula I) (Formula II) 3,8Z3,l l5 Patented July 9, 1974 The presentinvention may further be described as a process for stabilizingpolyolefin against oxidative deterioration which comprises incorporatingwith said polyolefin from 0.01 percent to 10 percent by weight of aphenolic compound of Formula H.

By alkyl in Formula H we mean to include primary, secondary and tertiaryalkyl with the further proviso that at least one of the groups R R R orR, be a primary alkyl group wherein there is at least one alkyl branchon the carbon atom in said primary alkyl group beta to the phenylenegroup to which it is attached or an aralkyl group wherein there is nobranching on the carbon alpha to the phenylene group. We prefer that thealkyl in Formula II contains from 1 to 10 carbon atoms. Of course, wherethe alkyl group has beta branching, the group must contain at least 4carbon atoms. It is particularly preferred that all the alkyl groups inFormula H, R R R and R be primary alkyl groups wherein there is nobranching on the carbon atom alpha to the phenylene group but there beone alkyl branch on the beta carbon.

By aralkyl in Formula II we are to be understood to mean a group of thefollowing structure:

wherein R and R are hydrogen or alkyl having 1 to 6 carbon atoms; X ishydrogen, alkyl, alkoxy, or halogen, and n is an integer between 0 and 5inclusive with the further proviso that at least one of the groups R R Ror R, be an aralkyl group wherein there is no alkyl branching on thecarbon alpha to the phenylene group or be a primary alkyl group whereinthere is at least one alkyl branch on the carbon atom in said primaryalkyl group beta to the phenylene group. We prefer that the aralkylgroup contains less than 20 carbon atoms. Where the aralkyl group issubstituted with halogen, the halogen group may be chloro, bromo, iodoor fluoro for example. Where the aralkyl group is substituted with alkylor alkoxy groups, these groups preferably contain from 1 to 13 carbonatoms which may be straight or branched chain. Suitable aralkyl groupsinclude the following as long as the above mentioned proviso issatisfied: benzyl styryl, ar-chlorobenzyl, ar-bromobenzyl,ar-iodobenzyl, ar-fluorobenzyl, ar-methoxybenzyl, ar-ethoxybenzyl,armethylbenzyl, ar-ethylbenzyl, or ar-tert-butylbenzyl.

Examples of specific phenolic compounds within the scope of Formula IIand useful in the practice of this invention are the following:

4,4-methylenebis (Z-methyl-6-isobutylphenol) 4,4'-methylenebis[2-ethyl-6- (2"-methylbutyl) phenol] 4,4'-m ethylenebis [2-isopropyl-6-2 -methylpentyl) phenol] 4,4-methylenebis[2-tertFbutyl-6-(2"-ethylhexy1) phenol]4,4'-methylenebis(2,6-diisobutylphenol) 4,4-methylenebis [2,6-(2"-methylbutyl) phenol] 4,4'-methylenebis[2,6- 2-methylpentyl) phenol];4,4'-methylenebis [2,6- (2-ethylpentyl) phenol] 4,4'-methylenebis [2,6-(2"-methylhexyl) phenol] 4,4'-methylenebis [2, 6- (2"-ethylhexyl phenol]4,4'-methylenebis [2,6-( "-methyloctyl) phenol] 4,4'-methyleneb is [2,6- 2-ethylo ctyl) phenol] 4,4'-methylenebis(2,6-dibenzylphenol)4,4'-methylenebis [2,6-di (p-chlorobenzyl) phenol]; 4,4'-methylenebis[2,6-di (p -methylbenzyl) phenol] 4,4'-methylenebis [2,6-di(p-ethylbenzyl phenol] 4,4'-methylenebis [2,6-di(p-methoxybenzyl)phenol]; 4,4'-methylenebis [2,6-di(p-ethoxybenzyl) phenol] (Formula III)The phenolic compounds of Formula II are prepared according to methodswell known in the art by reacting formaldehyde with a phenol of thefollowing formula:

(Formula IV) I polymers derived from monoolefins having a terminaldouble bond. Examples of such alpha polyolefins include but are notlimited to the following: polyethylene, polypropylene,poly-4-methylpentene-1, poly-l-butene, poly-3- methylbutene-l, andcopolymers thereof.

In general, the phenolic compound of Formula II should be used withpolyolefin in an amount elfective and suflicient to stabilize thematerial. The requisite amount will, of course, depend both on theefliciency of the particular phenolic compound and the nature of thepolyolefin to be stabilized. It has been our experience that from 0.01percent to percent by weight based on the weight of the polyolefin issufficient. Amounts down to as little as 0.0001 percent by weight may beeffective in some cases.

It is to be understood that the stabilizing effect of the phenoliccompounds is considerably enhanced by conventional synergists such ascertain sulfides and polysulfides. The synergist is used in conventionalamounts. For example, an amount of synergist from about 0.1 percent toabout 1 percent by weight of the organic material to be stabilized issatisfactory but we prefer to use from 0.1 percent to 0.5 percent byweight.

As sulfides there may be mentioned dialkylsulfides, particularly whereinthe alkyl groups are long chain such as dodecyl groups since the lowerdialkylsulfides are DESCRIPTION OF THE PREFERRED EMBODIMENTS Thefollowing embodiments of this invention are shown for the purpose ofillustrating the invention and demonstrate the best mode for practicingthe invention. It will be apparent to those skilled in the art thatvarious changes and modifications may be made therein without departingfrom the spirit and scope of the invention as it is more preciselydefined in the subjoined claims.

Example 1 In a reaction vessel equipped with a stirrer, condenser,thermometer, and dropping funnel was placed a solution of 17 g. ofparaformaldehyde and 278 g. of 2,6-di-pmethylbenzylphenol in 500 g; ofethanol. To this stirred solution maintained under a nitrogen atmosphereat 40 C. was added sulfuric acid in a dropwise manner until 250 g. hadbeen added. The mixture was stirred for 1 /2 hours, cooled, and thesolid filtered off. The product was Washed with water, filtered,recrystallized from ethanol, and dried. After drying the product whichwas 4,4- methylenebis(2,6-di-p-methylbenzylphenol) was obtained in 83percent yield and had a melting point of 123124 C.

Example 2 Using the equipment of Example 1, ml. of sulfuric acid wasadmixed with 210 ml. of ethanol. To this stirred solution maintainedunder a nitrogen atmosphere and at a temperature of 30 C. was added 7 g.of paraformaldehyde. At a temperature of about 50 C. a mixture of 105 g.of 2,6-dibenzylphenol in 60 ml. of ethanol was added to the abovestirred solution. The total admixture was maintained under a nitrogenatmosphere at about 4550 C. for about an hour. The admixture was cooledand the solid filtered off. The product was washed with water, filtered,and air dried. The dried product was extracted with n-hexane, filtered,and recrystallized from ethanol. The product was4,4-methylenebis(2,6-dibenzylphenol) which had a melting point of100-l02 C.

Example 3 Using the equipment of Example 1, 200 ml. of sulfuric acid wasadmixed with 400 ml. of ethanol. To this stirred solution maintainedunder a nitrogen atmosphere at 20-25 C. was added a mixture of 36 g. ofparaformaldehyde and 636 g. of 2,6-di(2"-ethylhexyl)phenol. The reactionmixture was maintained under a nitrogen atmosphere at 20=25 C.overnight. Then the reaction mixture was extracted with 2 liters ofn-hexane and 2 liters of water. The water was separated from the nhexanefraction and the n-hexane fraction Washed with 800 ml. of water. Thgwater was again separated from the n-hexane fraction and the fractionwas dried with MgSO The MgSO; was removed by filtration from then-hexane fraction and the n-hexane was stripped from the crude product.The unreacted 2,6-di(2"-ethylhexyl) phenol was removed from the crudeproduct by distillation under a reduced pressure of 0.18 mm. of Hg attemperatures up to 240 C. The product was 4,4'-methylenebis [2,6-di(2"-ethylhexyl) phenol] Example 4 The performance of several phenoliccompounds as antioxidants for polypropylene was determined in thefollowing tests:

In Test 1 an 80 g. sample of Hercules Pro-Fax 6501 polypropylene powderwas mixed in a Brabender Plasticorder in which the mixing chamber washeated to about 200 C. The material was mixed for 5 to 10 minutes untilthe polypropylene had a workable consistency. A sample of the materialwas then removed and molded into a 5 mil film. The one-inch diametercircles of the film were cut out and put into an oven maintained at C.After 1 hour in the oven, the sample crumbled.

In Test 2, 0.24 g. of dilaurylthiodipropionate was mixed with the 80-.g. of polypropylene powder and a sample tested for heat aging as inTest 1. The sample lasted for 70 hours before it crumbled.

The procedure of Test 1 was repeated in Test 3 except that 0.08 g. of4,4-methylenebis(2,6-di-tert-butylphenol) was added to the polypropylenepowder. A 5 mil film sample tested as in Test 1 lasted for 16 hoursbefore crumbling.

Test 4 was conducted like Test 2 except that 0.08 g. of4,4'-methylenebis(2,6-di-tert-butylphenol) was also incorporated intothe polypropylene powder. The-sample from this test lasted for 211hours.

Test 5 was conducted similarly to Test 1 except that 0.08 g. of 4,'-methylenebis[2,6-di(2"-ethylhexyl)phenol] prepared in Example 3 wasadded to the polypropylene powder. The sample lasted for 16 hours.

In Test 6 the procedures of Test 2 was repeated except that 0.08 g. of4,4-methylenebis[2,6-di(2-ethylhexyl)phenol] prepared in Example 3 wasalso added to the polypropylene powder. The sample in this test lastedfor 691 hours.

The procedure of Test 1 was repeated in Test 7 except that 0.08 g. of4,4-methylenebis (2,6-dibenzylphenol) prepared in Example 2 was added tothe polypropylene powder. A mil sample tested as in Test 1 lasted for 73hours before crumbling.

Test 8 was conducted like Test 2 except that 0.08 g. of 4,4'methylenebis(2,6-dibenzylphenol) was also incorporated into thepolypropylene powder. A sample from this test lasted for 837 hoursbefore crumbling.

Example 5 4,4-Methylenebis[2,6-di(2" ethylhexyl)phenol] from Example 3and 4,4'-methylenebis'2,6-di-tert-butylphenol) were evaluated in thisexample as antioxidants for turbine oil. A modification of ASTMD943-IP157 was used. The following modifications were made: 15 inches ofelectrolylic copper wire No. 14 Brown and Sharpe gage and 15 inches oflow-metalloid steel wire No. 16 Washburn and Moen gage were used to windthe mandrel; 150 ml. of an unstabilized base oil sold by American OilCompany was used; oil temperature was held at 150 C. during the test;and air was substituted for oxygen.

In Test 9, 0.63 g. of 4,4-methylenebis(2,6-di-tert-butylphenol) wasadded to the oil. Every 24 hours a 5-10 g. sample of oil was removedfrom the oil tube. The acid number (mg KOH/g. sample) of the sample wasdetermined and the time required to reach an acid number of 2.0 wasdetermined. In this test it took 5 days for the acid number to reach2.0.

Following the above procedure in Test the effectiveness of4,4-methylenebis[2,6-di(2"-ethylhexyl)phenol] in place of the 4,4methylenebis(2,6-di-tert-butylphenol) as a stabilizer for turbine oilwas determined. In this test it took 2 days for the acid number of theoil to reach 2.0.

Test 11 was conducted like Test 9 except that4,4-methylenebis(2,6-dibenzylphenol) was used in place of the4,4-methylenebis(2,6-di-zert-butylphenol). In this test it took 2 daysfor the acid number of the oil to reach 2.0.

The above examples clearly demonstrate the accomplishment of thisinvention. Examples 1-3 demonstrate our preferred method for obtainingthe phenolic compounds useful in our invention.

In Example 4 a comparison of Tests 5 and 7 with Test 3 clearlydemonstrates the unexpected superiority of phenolic compounds of FormulaII as antioxidants in polypropylene over the conventional antioxidant4,4-methylcnebis(2,6-di-tert-butylphenol). This superiority is evenbetter demonstrated by a comparison of Tests 6 and 8 with Test 4 whereina conventional synergist is used with the antioxidant. Tests 14inclusive are not embodiments of our invention but were prepared for thepurposes of comparison with Tests 5-8 inclusive.

In Example 5 a comparison of Test 9 with Test 10 and 11 shows thatphenolic compounds of Formula H do not distinguish themselves asantioxidants in turbine oils in comparison with 4,4methylenebis(2,6-di-tert-butylphe- 1101). Tests 9-11 inclusive are notembodiments of our invention but were prepared to compare with theresults of Example 4. The excellent ability of phenolic com pounds ofFormula II to stabilize polypropylene in Example 4 as compared to thatof 4,4'-methylenebis(2,6-ditert-butylphenol) is unexpected in view oftheir lackluster performance in Example 5 in turbine oil.

From the foregoing description we consider it to be clear that thepresent invention contributes a substantial benefit to the antioxidantart by providing a new and useful antioxidant for polyolefin.

6 We claim: 1. Polymonoolefin stabilized with the combination ofeffective amounts of a sulfide synergist and a phenolic compound havingthe following structural formula:

R1 R1 HO@CHr-@OH I I wherein R R R and R are independently aralkyl oralkyl; wherein aralkyl is a group of the structure:

1.. wherein R and R are hydrogen or alkyl having 1 to 6 carbon atoms; Xis alkyl, alkoxy, or halogen and n is an integer between 0 and 5inclusive; with the proviso that at least one aralkyl group contains nobranching on the carbon alpha to the phenol phenylene group or at leastone alkyl group contins no branching on the carbon alpha to the phenolphenylene group but has at least one branch on the carbon beta to thephenol phenylene group, wherein the synergist is present in an amountbetween 0.1 percent to 1 percent, and said phenolic compound is presentin an amotmt between .0001 percent and 10 percent by weight based on theweight of the polymonoolefin.

2. The composition of Claim 1 wherein a long chain dialkylsulfide ispresent as the synergist.

3. The composition of Claim 2 wherein R R R and R are alkyl groupscontaining from 1 to 10 carbon atoms.

4. The composition of Claim 2 wherein R R and R and R are aralkyl groupscontaining less than 20 carbon atoms.

5. The composition of Claim 4 wherein the aralkyl groups are substitutedwith alkyl, alkoxy or halogen groups.

6. The composition of Claim 2 wherein the phenolic compound is4,4-methylenebis(2,6-di-isobutylphenol).

7. The composition of Claim 2 wherein the phenolic compound is 4,4methylenebis[2,6-di(2"-methylbutyl) phenol].

8. The composition of Claim 2 wherein the phenolic compound is 4,4methylenebis[2,6-di(2" ethylbutyl) phenol].

9. The composition of Claim 2 wherein the phenolic compound is 4,4methylenebis[2,6 di(2"-ethylhexyl) phenol].

10. The composition of Claim 2 wherein the phenolic compound is4,4-methylenebis(2,6-dibenzylphenol).

11. The composition of Claim 2 wherein the phenolic compound is 4,4methylenebis[2,6-di(o-chlorobenzyl) phenol].

12. The composition of Claim 2 wherein the phenolic compound is 4,4methylenebis[2,6-di(p-methylbenzyl) phenol].

13. The composition of Claim 2 wherein the phenolic compound is4,4-methylenebis[2,6-di(p-methoxybenzyl) phenol].

14. The composition of Claim 2 wherein the phenolic compound is 4,4methylenebis[2,6-di(p ethoxybenzyl) phenol].

15. A process for stabilizing polyolefin which comprises incorporatingwith said polyolefin from 0.01 percent to 0.5 percent by weight of adialkylsulfide as a synergist and 0.01 percent to 10 percent by weightof a phenolic compound having the following structural formula:

wherein R R R and R are independently aralkyl or alkyl with the provisothat at least one aralkyl group contains no branching on the carbonalpha to the phenylene group or at least one alkyl group contains nobranching on the carbon alpha to the phenylene group but has at leastone branch on the carbon beta to the phenylene group.

16. The process as in Claim 15 wherein the phenolic compound is4,4-methylenebis(2,6-di-isobutylphenol); 4, 4 methy1enebis[2,6di(2"-methylbutyl)phenol]; 4,4-methylenebis[2,6-di(2-ethylbutyl)phenol]; 4,4methylenebis[2,6-di(2-ethylhexyl)phenol]; 4,4 methylenebis(2,6-dibenzylphenol) 4,4-methyleneb'is [2,6-di(p-chlorobenzyl)phenol];4,4 methy1enebis[2,6 di(p-methy1- benzyl) phenol]; 4,4 methylencbis[2,6di(methoxy- 8 benzyl)phenol]; or 4,4 methylenebis[2,6-di(p-ethoxybenzyl)phenol] References Cited 10 MELVYN I. MARQUIS, Primary Examiner US. Cl.X.R.

26045.75 K, 45.8 S, 610 R

